A typical structure formed during the manufacture of a semiconductor memory device is a container cell which requires several steps for its manufacture. A sample process for forming the container cell includes implanting a diffusion area in a semiconductor wafer substrate, and forming an insulator, such as borophosphosilicate glass (BPSG) or tetraethylorthosilicate (TEOS), over the wafer. The insulator is etched to open a contact, usually round or oval in shape, to expose the diffusion region. A compliant conductive layer such as doped polycrystalline silicon is formed over the wafer surface and within the contact which contacts the diffusion region. The conductive layer is masked to protect the portion within the contact and the remainder is etched. Various steps as known in the art are subsequently performed to produce a container cell.
The process described above requires the wafer to be transported between several chambers. The diffusion region is formed in an implanter, and the insulator, usually a blanket layer, is formed either in a furnace (to form TEOS) or in a chemical vapor deposition tool such as a Watkins-Johnson to form BPSG. Plasma-enhanced chemical vapor deposition (PECVD) and various other means can be used to form the insulator. The wafer is then moved to a stepper for patterning of the insulator, then to a dry etch chamber where the insulator is etched to form the contact. The wafer is moved again to a furnace, a low-pressure chemical vapor deposition (LPCVD) chamber, or a PECVD chamber to form a blanket conductive layer over the wafer surface and within the contact. Next, the conductive layer on the surface of the wafer is removed, for example using chemical mechanical planarization (CMP) equipment. The conductive layer can also be removed by forming a resist coat over the wafer, which forms a thicker layer within the contact than on the wafer surface, and dry etching the surface to remove the resist and poly from the surface while leaving a portion of the poly within the contact. Finally, the wafer is moved to an acid bath or a plasma etcher where the resist is stripped from the contact.
Transporting the wafer is not desirable as it increases processing time, costs, and possible damage and contamination to the wafer. A process which requires less wafer transportation is therefore desirable.
It should be emphasized that the drawings herein are not to scale but are merely schematic representations and are not intended to portray the specific parameters or the structural details of the invention, which can be determined by one of skill in the art by examination of the information herein.